In the Konkan region of Maharashtra, in Ratnagiri district, lies the village of Devtali in Guhagar taluka, where for the past fifteen years a terrifying pattern has remained unquestioned. Every year, on the night of Holi Pournima, one person dies, and the villagers believe these deaths are divine punishments delivered by Shankasur, a feared divine asura figure worshipped during the Shimga festival. These deaths are accepted as God's will until the arrival of a new police inspector, Vishwas Saranjame, who openly challenges the belief and declares that what the village calls faith is actually a pattern of murder hidden behind fear and ritual. Soon after, a man named Rajan Nimkar is found dead in the village pond, and the villagers immediately announce that Shankasur has punished another sinner. Vishwas orders a post mortem and begins a detailed investigation, during which he finds a gold chain near the pond that leads him to Shankar Mahadik, a young man who had publicly fought with Rajan and owed him money. Shankar is arrested, triggering violent protests from villagers who accuse the police of insulting their god. The medical report complicates the case further, revealing drowning as the cause of death along with signs of struggle, skin fragments between Rajan's teeth, white hair clenched in his hand, and whip like marks on his body. As the investigation progresses, the evidence begins to blur when DNA reports rule out Shankar, the white hair is identified as wild cow hair, and the whip marks are traced to nylon cloth, all materials used in the Shankasur costume. Vishwas turns his suspicion toward the three Shankasur performers of Devtali, Ganesh Korde, Sadanand Rangne, and Raghunath Pawase, but with no direct proof and rising political pressure, he is forced to release them, strengthening the villagers' belief that Shankasur is real and beyond the law. Determined to find the truth, Vishwas reopens old murder files from fifteen years ago and notices wool fibers in two cases, even though wool is not used in Devtali's Shankasur saaj. His search leads him to the village tailor Shafiq, who reveals that such wool is used in the Shankasur costume of another village called Palner. This detail alerts Vishwas to Raghunath Pawase's connection to Palner, and a search of his house uncovers a Shankasur mask with distinctive woolen tassels. Raghunath's strange emotional reaction to the mask raises further suspicion, pushing Vishwas to investigate his past in Palner, where he uncovers a childhood filled with abuse, bullying, and a distorted idea of divine justice. Vishwas learns that Raghunath suffers from Multiple Identity Disorder and truly believes he is Shankasur, committing murders under this delusion. Forensic tests finally confirm that the wool fibers and whip marks match Raghunath's costume, while the skin fragments are traced to a separate domestic incident, clearing other suspects. Vishwas arrests Raghunath and sends him for psychiatric treatment, finally ending a cycle of ritualistic killings and forcing Devtali to confront the horrifying truth that their god was only a mask worn by a fractured mind.